NASA uses different types of cameras, one of them is INFRARED (appears black & white or green to human eyes), this picks up light we can't see. A scientist (I don't remember his name) in the 1950's noticed objects flying around in the sky when he turned his camera upward. The scientist came to the shocking conclusion that WE ARE NOT ALONE. And besides, the really good quality footage is hidden from the public's eyes by our governments, they don't want people to panic.
Also, blurry imagines are either accidental by excited people with shakey hands, or intentionally distorted by a hoaxer.